As part of a growing number of blood pressure drug recalls, Torrent Pharmaceuticals has expanded its recall of losartan medication over concerns it contains a carcinogen.

Torrent said six additional lots of losartan potassium and hydrochlorothiazide tablets contain trace amounts of the probable human carcinogen N-nitrosodiethylamine (NDEA), according to a notice shared Tuesday by the Food and Drug Administration.

The India-based pharmaceutical company has already recalled 10 lots of losartan potassium tablets in the past two months, and since July, more than a dozen other recalls have been issued for common blood pressure medications.

The recalls have been linked to two overseas factories that made the drugs' active ingredients, which the FDA has said it is investigating. The drugs have been found to contain either NDEA or N-Nitrosodimethylamine (NDMA).

Various versions of valsartan, losartan and irbesartan drugs have been part of the recalls. These medications are part of a large class called angiotensin II receptor blockers (ARBs), which lower blood pressure by widening or relaxing blood vessels.

The agency is telling patients to continue taking their medication "as the risk of harm to the patient's health may be higher if the treatment is stopped immediately without any alternative treatment," the FDA said.